Organic light-emitting device and apparatus including the same

Abstract

An organic light-emitting device and an apparatus including the organic light-emitting device.

What is claimed is: 
     
       1. An organic light-emitting device comprising:
 a first electrode; 
 a second electrode; and 
 an organic layer between the first electrode and the second electrode, 
 wherein the organic layer comprises an emission layer, the emission layer comprises a first compound, a second compound, and a third compound, the first compound is represented by Formula 1, the second compound is represented by Formula 2, the third compound is represented by Formula 3, and the first compound, the second compound, and the third compound are different from one another: 
 
       
         
           
           
               
               
           
         
         wherein in Formulae 1 to 3, 
         A 11  is a group represented by Formula 10: 
       
       
         
           
           
               
               
           
         
         wherein, in Formula 10, 
         R 101  to R 108  are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 10  alkyl group, a C 2 -C 10  alkenyl group, a C 2 -C 10  alkynyl group, a C 1 -C 10  alkoxy group, a C 3 -C 10  cycloalkyl group, a heterocycloalkyl group having 1 to 10 ring-forming atoms, a C 3 -C 15  cycloalkenyl group, a heterocycloalkenyl group having 1 to 15 ring-forming atoms, a C 8 -C 15  aryl group, a C 6 -C 15  aryloxy group, a C 6 -C 15  arylthio group, a heteroaryl group having 1 to 15 ring-forming atoms, a heteroaryloxy group having 1 to 15 ring-forming atoms, a heteroarylthio group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed polycyclic group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed heteropolycyclic group having 1 to 15 ring-forming atoms, —C(Q 1 )(Q 2 )(Q 3 ), —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), —N(Q 1 )(Q 2 ), —P(Q 1 )(Q 2 ), —C(═O)(Q 1 ), —S(═O)(Q 1 ), —S(═O) 2 (Q 1 ), —P(═O)(Q 1 )(Q 2 ), and —P(═S)(Q 1 )(Q 2 ), 
         k11 and k12 are each independently selected from 1, 2, 3, and 4, 
         R 11  is selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 10  alkyl group, a C 2 -C 10  alkenyl group, a C 2 -C 10  alkynyl group, a C 1 -C 10  alkoxy group, a C 3 -C 10  cycloalkyl group, a heterocycloalkyl group having 1 to 10 ring-forming atoms, a C 3 -C 15  cycloalkenyl group, a heterocycloalkenyl group having 1 to 15 ring-forming atoms, a C 6 -C 15  aryl group, a C 6 -C 15  aryloxy group, a C 6 -C 15  arylthio group, a heteroaryl group having 1 to 15 ring-forming atoms, a heteroaryloxy group having 1 to 15 ring-forming atoms, a heteroarylthio group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed polycyclic group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed heteropolycyclic group having 1 to 15 ring-forming atoms, —C(Q 1 )(Q 2 )(Q 3 ), —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), —N(Q 1 )(Q 2 ), —P(Q 1 )(Q 2 ), —C(═O)(Q 1 ), —S(═O)(Q 1 ), —S(═O) 2 (Q 1 ), —P(═O)(Q 1 )(Q 2 ), and —P(═S)(Q 1 )(Q 2 ), 
         L 21  to L 23  are each independently selected from a C 5 -C 15  carbocyclic group and a heterocyclic group having 1 to 15 ring-forming atoms, each unsubstituted or substituted with at least one substituent selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 10  alkyl group, a C 2 -C 10  alkenyl group, a C 2 -C 10  alkynyl group, a C 1 -C 10  alkoxy group, a C 3 -C 10  cycloalkyl group, a heterocycloalkyl group having 1 to 10 ring-forming atoms, a C 3 -C 15  cycloalkenyl group, a heterocycloalkenyl group having 1 to 15 ring-forming atoms, a C 6 -C 15  aryl group, a C 6 -C 15  aryloxy group, a C 6 -C 15  arylthio group, a heteroaryl group having 1 to 15 ring-forming atoms, a heteroaryloxy group having 1 to 15 ring-forming atoms, a heteroarylthio group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed polycyclic group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed heteropolycyclic group having 1 to 15 ring-forming atoms, —C(Q 31 )(Q 32 )(Q 33 ), —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), —N(Q 31 )(Q 32 ), — P(Q 31 ) (Q 32 ), —C(═O)(Q 1 ), —S(═O)(Q 31 ), —S(═O) 2 (Q 31 ), —P(═O)(Q 31 )(Q 32 ), and —P(═S)(Q 31 )(Q 32 ), 
         a21 to a23 are each independently selected from 0, 1, and 2, 
         R 21  to R 23  are each independently selected from a C 3 -C 15  cycloalkenyl group, a heterocycloalkenyl group having 1 to 15 ring-forming atoms, a C 6 -C 15  aryl group, a C 6 -C 15  aryloxy group, a C 6 -C 15  arylthio group, a heteroaryl group having 1 to 15 ring-forming atoms, a heteroaryloxy group having 1 to 15 ring-forming atoms, a heteroarylthio group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed polycyclic group having 1 to 15 ring-forming atoms, and a monovalent non-aromatic condensed heteropolycyclic group having 1 to 15 ring-forming atoms, each unsubstituted or substituted with at least one substituent selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 10  alkyl group, a C 2 -C 10  alkenyl group, a C 2 -C 10  alkynyl group, a C 1 -C 10  alkoxy group, a C 3 -C 10  cycloalkyl group, a heterocycloalkyl group having 1 to 10 ring-forming atoms, a C 3 -C 15  cycloalkenyl group, a heterocycloalkenyl group having 1 to 15 ring-forming atoms, a C 6 -C 15  aryl group, a C 6 -C 15  aryloxy group, a C 6 -C 15  arylthio group, a heteroaryl group having 1 to 15 ring-forming atoms, a heteroaryloxy group having 1 to 15 ring-forming atoms, a heteroarylthio group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed polycyclic group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed heteropolycyclic group having 1 to 15 ring-forming atoms, —C(Q 31 )(Q 32 )(Q 33 ), —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), —N(Q 31 )(Q 32 ), —P(Q 31 )(Q 32 ), —C(═O)(Q 1 ), —S(═O)(Q 31 ), —S(═O) 2 (Q 31 ), —P(═O)(Q 31 )(Q 32 ), and —P(═S)(Q 31 )(Q 32 ); and 
         —C(Q 1 )(Q 2 )(Q 3 ), —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), —N(Q 1 )(Q 2 ), —P(Q 1 )(Q 2 ), —C(═O)(Q 1 ), —S(═O)(Q 1 ), —S(═O) 2 (Q 1 ), —P(═O)(Q 1 )(Q 2 ), and —P(═S)(Q 1 )(Q 2 ), 
         X 31  is selected from N(R 39 ) and C(R 39 )(R 40 ), 
         R 31  to R 40  are each independently selected from a group represented by *-(L 31 ) a31 -A 31 , hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 10  alkyl group, a C 2 -C 10  alkenyl group, a C 2 -C 10  alkynyl group, a C 1 -C 10  alkoxy group, a C 3 -C 10  cycloalkyl group, a heterocycloalkyl group having 1 to 10 ring-forming atoms, a C 3 -C 15  cycloalkenyl group, a heterocycloalkenyl group having 1 to 15 ring-forming atoms, a C 6 -C 15  aryl group, a C 6 -C 15  aryloxy group, a C 6 -C 15  arylthio group, a heteroaryl group having 1 to 15 ring-forming atoms, a heteroaryloxy group having 1 to 15 ring-forming atoms, a heteroarylthio group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed polycyclic group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed heteropolycyclic group having 1 to 15 ring-forming atoms, —C(Q 1 )(Q 2 )(Q 3 ), —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), —N(Q 1 )(Q 2 ), —P(Q 1 )(Q 2 ), —C(═O)(Q 1 ), —S(═O)(Q 1 ), —S(═O) 2 (Q 1 ), —P(═O)(Q 1 )(Q 2 ), and —P(═S)(Q 1 )(Q 2 ), provided that at least one selected from R 31  to R 39  is a group represented by *-(L 3 ) a31 -A 31 , 
         L 31  is a phenylene group unsubstituted or substituted with at least one substituent selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 10  alkyl group, a C 2 -C 10  alkenyl group, a C 2 -C 10  alkynyl group, a C 1 -C 10  alkoxy group, a C 3 -C 10  cycloalkyl group, a heterocycloalkyl group having 1 to 10 ring-forming atoms, a C 3 -C 15  cycloalkenyl group, a heterocycloalkenyl group having 1 to 15 ring-forming atoms, a C 6 -C 15  aryl group, a C 6 -C 15  aryloxy group, a C 6 -C 15  arylthio group, a heteroaryl group having 1 to 15 ring-forming atoms, a heteroaryloxy group having 1 to 15 ring-forming atoms, a heteroarylthio group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed polycyclic group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed heteropolycyclic group having 1 to 15 ring-forming atoms, —C(Q 31 )(Q 32 )(Q 33 ), —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), —N(Q 31 )(Q 32 ), —P(Q 31 )(Q 32 ), —C(═O)(Q 1 ), —S(═O)(Q 31 ), —S(═O) 2 (Q 31 ), —P(═O)(Q 31 )(Q 32 ), and —P(═S)(Q 31 )(Q 32 ), 
         a31 is selected from 1, 2, and 3, and 
         A 31  is selected from a carbazolyl group and a fluorenyl group, each unsubstituted or substituted with at least one substituent selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 10  alkyl group, a C 2 -C 10  alkenyl group, a C 2 -C 10  alkynyl group, a C 1 -C 10  alkoxy group, a C 3 -C 10  cycloalkyl group, a heterocycloalkyl group having 1 to 10 ring-forming atoms, a C 3 -C 15  cycloalkenyl group, a heterocycloalkenyl group having 1 to 15 ring-forming atoms, a C 6 -C 15  aryl group, a C 6 -C 15  aryloxy group, a C 6 -C 15  arylthio group, a heteroaryl group having 1 to 15 ring-forming atoms, a heteroaryloxy group having 1 to 15 ring-forming atoms, a heteroarylthio group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed polycyclic group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed heteropolycyclic group having 1 to 15 ring-forming atoms, —C(Q 31 )(Q 32 )(Q 33 ), —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), —N(Q 31 )(Q 32 ), —P(Q 31 )(Q 32 ), —C(═O)(Q 1 ), —S(═O)(Q 31 ), —S(═O) 2 (Q 31 ), —P(═O)(Q 31 )(Q 32 ), and —P(═S)(Q 31 )(Q 32 ), 
         wherein Q 1  to Q 3  and Q 31  to Q 33  are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, C 1 -C 10  alkyl group, a C 2 -C 10  alkenyl group, a C 2 -C 10  alkynyl group, a alkoxy group, a C 3 -C 10  cycloalkyl group, a heterocycloalkyl group having 1 to 10 ring-forming atoms, a C 3 -C 15  cycloalkenyl group, a heterocycloalkenyl group having 1 to 15 ring-forming atoms, a C 6 -C 15  aryl group, a C 6 -C 15  aryloxy group, a C 6 -C 15  arylthio group, a heteroaryl group having 1 to 15 ring-forming atoms, a heteroaryloxy group having 1 to 15 ring-forming atoms, a heteroarylthio group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed polycyclic group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed heteropolycyclic group having 1 to 15 ring-forming atoms, a biphenyl group, and a terphenyl group, and 
         * indicates a binding site to an adjacent atom, and 
         wherein the organic light-emitting device emits delayed fluorescence. 
       
     
     
       2. The organic light-emitting device of  claim 1 , wherein k11 and k12 are each independently selected from 1 and 2. 
     
     
       3. The organic light-emitting device of  claim 1 , wherein the first compound is represented by any one of Formulae 1-1 to 1-58: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 1-1 to 1-58, 
         A 11a  and A 11b  are each understood by referring to the description of A 11  in Formula 1, and 
         R 11a , R 11b , and R 11c  are each understood by referring to the description of R 11  in Formula 1. 
       
     
     
       4. The organic light-emitting device of  claim 1 , wherein A 11  is represented by any one of Formulae 10-1 and 10-2: 
       
         
           
           
               
               
           
         
         wherein, in Formulae 10-1 and 10-2, 
         R 103  and R 106  are each independently selected from —F, a cyano group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a benzoisoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a benzoquinoxalinyl group, a benzoquinazolinyl group, an azafluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, a diazafluorenyl group, a diazacarbazolyl group, a diazadibenzofuranyl group, and a diazadibenzothiophenyl group, and 
         * indicates a binding site to an adjacent atom. 
       
     
     
       5. The organic light-emitting device of  claim 1 , wherein R 11  is selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 10  alkyl group, a C 3 -C 15  cycloalkenyl group, a heterocycloalkenyl group having 1 to 15 ring-forming atoms, a C 6 -C 15  aryl group, a heteroaryl group having 1 to 15 ring-forming atoms, a monovalent non-aromatic condensed polycyclic group having 1 to 15 ring-forming atoms, and a monovalent non-aromatic condensed heteropolycyclic group having 1 to 15 ring-forming atoms. 
     
     
       6. The organic light-emitting device of  claim 1 , wherein R 11  is hydrogen. 
     
     
       7. The organic light-emitting device of  claim 1 , wherein L 21  to L 23  are each independently selected from a benzene group, a naphthalene group, a phenalene group, an anthracene group, a phenanthrene group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a benzoisoquinoline group, a phthalazine group, a naphthyridine group, a quinoxaline group, a quinazoline group, a benzoquinoxaline group, a benzoquinazoline group, a fluorene group, a carbazole group, a dibenzofuran group, a dibenzothiophene group, an azafluorene group, an azacarbazole group, an azadibenzofuran group, an azadibenzothiophene group, a diazafluorene group, a diazacarbazole group, a diazadibenzofuran group, and a diazadibenzothiophene group, each unsubstituted or substituted with at least one substituent selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a benzoisoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a benzoquinoxalinyl group, a benzoquinazolinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an azafluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, a diazafluorenyl group, a diazacarbazolyl group, a diazadibenzofuranyl group, and a diazadibenzothiophenyl group, and
 a21 to a23 are each independently selected from 0 and 1. 
 
     
     
       8. The organic light-emitting device of  claim 1 , wherein R 21  to R 23  are each independently selected from a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a benzoisoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a benzoquinoxalinyl group, a benzoquinazolinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an azafluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, a diazafluorenyl group, a diazacarbazolyl group, a diazadibenzofuranyl group, and a diazadibenzothiophenyl group, each unsubstituted or substituted with at least one substituent selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a benzoisoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a benzoquinoxalinyl group, a benzoquinazolinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an azafluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, a diazafluorenyl group, a diazacarbazolyl group, a diazadibenzofuranyl group, a diazadibenzothiophenyl group, —C(Q 31 )(Q 32 )(Q 33 ), —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), —N(Q 31 )(Q 32 ), —P(Q 31 )(Q 32 ), —C(═O)(Q 1 ), —S(═O)(Q 31 ), —S(═O) 2 (Q 31 ), —P(═O)(Q 31 )(Q 32 ), and —P(═S)(Q 31 )(Q 32 ); and
 —C(Q 1 )(Q 2 )(Q 3 ), —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), —N(Q 1 )(Q 2 ), —P(Q 1 )(Q 2 ), —C(═O)(Q 1 ), —S(═O)(Q 1 ), —S(═O) 2 (Q 1 ), —P(═O)(Q 1 )(Q 2 ), and —P(═S)(Q 1 )(Q 2 ), 
 wherein Q 1  to Q 3  and Q 31  to Q 33  are each independently selected from a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a benzoisoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a benzoquinoxalinyl group, a benzoquinazolinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an azafluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, a diazafluorenyl group, a diazacarbazolyl group, a diazadibenzofuranyl group, and a diazadibenzothiophenyl group. 
 
     
     
       9. The organic light-emitting device of  claim 1 , wherein at least one selected from R 21  to R 23  is selected from a group represented by Formula 7-1, a group represented by Formula 7-2, —C(Q 1 )(Q 2 )(Q 3 ), and —Si(Q 1 )(Q 2 )(Q 3 ): 
       
         
           
           
               
               
           
         
         wherein, in Formulae 7-1 and 7-2, 
         Y 71  is selected from a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, —C(Q 31 )(Q 32 )(Q 33 ), and —Si(Q 31 )(Q 32 )(Q 33 ), 
         R 71  to R 74  are each independently selected from hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, —C(Q 31 )(Q 32 )(Q 33 ), and —Si(Q 31 )(Q 32 )(Q 33 ), 
         Q 1  to Q 3  and Q 31  to Q 33  are each independently selected from a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, and 
         * indicates a binding site to an adjacent atom. 
       
     
     
       10. The organic light-emitting device of  claim 1 , wherein X 31  is N(R 39 ). 
     
     
       11. The organic light-emitting device of  claim 1 , wherein R 31  to R 40  are each independently selected from a group represented by *-(L 31 ) a31 -A 31 , hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, provided that at least one selected from R 31  to R 39  is the group represented by *-(L 31 ) a31 -A 31 . 
     
     
       12. The organic light-emitting device of  claim 1 , wherein L 31  is a phenylene group unsubstituted or substituted with at least one substituent selected from a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, and
 a31 is selected from 1 and 2. 
 
     
     
       13. The organic light-emitting device of  claim 1 , wherein A 31  is represented by any one of Formulae 8-1 to 8-5: 
       
         
           
           
               
               
           
         
         wherein, in Formulae 8-1 to 8-5, 
         R 81  to R 89  are each independently selected from hydrogen, a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, and 
         * indicates a binding site to an adjacent atom. 
       
     
     
       14. The organic light-emitting device of  claim 1 , wherein the third compound is represented by any one of Formulae 3-1 to 3-5: 
       
         
           
           
               
               
           
         
         wherein, in Formulae 3-1 to 3-5, 
         L 31 , a31, A 31 , and R 31  to R 39  are respectively understood by referring to the descriptions of L 31 , a31, A 31 , and R 31  to R 39  in Formula 3. 
       
     
     
       15. The organic light-emitting device of  claim 1 , wherein the first compound is selected from Group I, the second compound is selected from Group II, and the third compound is selected from Group III: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
       16. The organic light-emitting device of  claim 1 , wherein the first compound is a delayed fluorescence emitter. 
     
     
       17. The organic light-emitting device of  claim 1 , wherein the third compound has a maximum emission wavelength in a range of about 450 nanometers (nm) to about 550 nm. 
     
     
       18. The organic light-emitting device of  claim 1 , wherein the delayed fluorescence is in a range of about 450 nm to about 550 nm. 
     
     
       19. The organic light-emitting device of  claim 1 , wherein
 the first electrode is an anode, 
 the second electrode is a cathode, and 
 the organic layer further comprises a hole transport region between the first electrode and the emission layer and/or an electron transport region between the emission layer and the second electrode, 
 the hole transport region comprises a hole injection layer, a hole transport layer, an emission auxiliary layer, an electron blocking layer, or a combination thereof, and 
 the electron transport region comprises a hole blocking layer, an electron transport layer, an electron injection layer, or a combination thereof. 
 
     
     
       20. An apparatus comprising: a thin-film transistor comprising a source electrode, a drain electrode, and an active layer; and the organic light-emitting device of  claim 1 , wherein the first electrode of the organic light-emitting device is electrically connected to any one of the source electrode and the drain electrode of the thin-film transistor.